Apparatus for annealing glass



` J. W. CRUIKSHANK.

APPARATUS FOR ANNEALING GLASS.

APPLICATION FILED 050.20.1911.

IN VEA/TOR.

J. W. CRUIKSHANK.

APPARATUS FOR ANNEALING GLASS.

APPLICATION FILI-:D DEc.2o.I.9I1.

Patented Aug. 12, 1919.

SHEETS-SHEETZ.

INVENTOR UNITED sTATEs PATENT oEPIcE.

JAMES w. CEUIKSHANK, 0E PITTSBURGH, PENNSYLVANIA, AssIGNoE To J. W. CEUIESHANK ENGINEERING COMPANY, 0E PITTSBURGH, PENNSYLVANIA APPARATUS EOE ANN-EALING- GIAss.

T 0 all whom'zt-may concern.'

.Be it known that I, JAMES lV. CRUIK- lsHANK, citizen of the United Sta-tes, resiplate glass annealing leers for the better,

cooling of the sheets. Heretofore difliculty has been experienced in bringing the sheets out of the delivery end of the leer at a sufficiently low temperature so that when eX- posed to cold air drafts breakage will not occur especially in winter. Attempts have been made 'to'accomplish the desired result by making the leer runway of extreme length with the corresponding disadvantages of additional expense forconstruction, increased length of rods and possible resulting disarrangement of the machinery. This increase in length is impracticable in' most factorie-s on account of'the space required, moreover the glass during its passage through the leer runway after it has been cooled below a certain temperature will radiate its heat very slowly so that even if the length ofthe .leer is increased the desired lresults are lnot obtained and the advantage of the continuation of the length of the runway will not reduce the temperature to an appreciable extent commensurate with the disadvantages.

The sheets of glass are moved forward in thel leer runwayfby that type of conveyer where the alternate `pulling of the traveling rods and the raisingof the xed supporting 'rods which allow the traveling rods to be returned to position for,v another draw. These draws are at regular intervals and for practical purposes the width of the sheet,

each sheet being advanced one place as a sheet is drawn. The Width ofthe sheet. de-

termines the length of the runway, it being the usual practice to construct it to contain a fixed number of sheets so that its length will vary as the width of the sheet/.

A rapid cooling due to the comparatively large difference of temperature between the plates and the walls and roof of the leer runway takes place at the hot end of the l A `Specification of 1.'.etters Patent.

from chec Patent-eil Aug. 12. 1919.

' Application led December 20, 1917. Serial No. 208.103.

vent too rapid cooling, but as the sheets advance the coollng becomes co1n} arat1vely slow, the resultlng curve showing the cooling effect, being on parabolic lines.

and becoming nearly parallel with the abscissa as the length of the leer runway is increased. This fact is obvious from the well known law of radiation which varies as Tf-t@t where T represents the absolute temperature of the surface of the heated object and t the absolute temperature of the surrounding surfaces which receive the radiated heat. It is evident therefore that y cooling by radiation will not produce results in the reduction of the temperature of the sheets to a point where they can leave the leer safely and be handle-d on the cut-ting table, more especially as heretofore, it .has been found necessary to draw heat down the iues under the runway to prevent the metal supportinor rods on which the glass is carried king the sheet and causing small vents in it which will eventually develop into large cracks. Unless heated, these rods are at. a lower temperature than the glass and absorb heat from it, thus causin these vents or cracks. To overcome this di culty I provide a contact surface for the rods of asbestos or other nonconduct-ing material. In order to produce a more rapid cooling of the glass sheets, I use the method of cooling by convection and allow access of air to the sheets at the lower end, by increasing the size of the leer runway or cooling ehambeen difficulty experienced in making the glass suiiiciently'cool in summer due to the higher temperature of the surrounding objects and breakage will occur in winter due Ico to the'lower temperature of the roo-f land walls in the building. I not only provide'a recipient surface for radiation of approxi.- mately constant temperature in the ceiling of the building containing thev leer, but also arrange for the control of the air current which at times have a tendency' to passup the-leer toward the hot end, due to atmos- 1,10

pheric conditions in the stack and adverse` winds which cause drafts in the building. Usually the stack provided at the end of the leer to draw the heat down the leer runway is a natural draft which it is evident will not be effective, is unconstant and unreliable as it is far removed from the source of heat. It is therefore often necessary to cause a draft by supplying an auxiliary source of heat directly to the stack. In my apparatus I employ a special form of stack using a fan with means -to produce a constant draft. This stack draws the gases, not only from the underfiues when required, but also through the leer way itelf over the surface of the sheets in accordance with the usual practice. I use the induced draft stack for this purpose and lead the air toward the end of the leer so as to prevent back drafts of cold air up the leer way.

Referring to the drawings:

Figure 1 is a plan view of a plate glass annealing leer and part of a furnace hall,

taken on section 1 1, Fig. 2.

Fig. 2 is a cross sectional elevation of the same on line 2 2, Figs. 1 and 3.

Fig. 3 is a horizontal section on line 3-3. Fig. 2.

Fig. 4 is .a cross sectional elevation on line 4 4, Figs. 1 and 2.

-Fig. 5 is a cross sectional view on line F1gs 1 and 2, the stack being for convenience shown on the opposite side in this view to that in Figs. 1 and 3.

olgsr and 7 are details of glass carrying r s.

'IIhe furnaces in which the glass is melted are represented by the numeral 1, 2 being the furnace hall building. 3 is the usual casting table and 4 the leer ovens in which are represented the 'outlines of plates of glass. The leer runway i's designa-ted by the numeral 5 terminating with carrying rods 6, shown in detail Figs. 6- and 7projecting therefrom and leading to a transfer car 7 mounted on a track 8, which conveys the glass sheet into a vestibule chamber 9 and thence to the cutting tables..

The leer runway is inclosed in the buildlng 10 with roof trusses 11 and walls 12. The leer runway is covered by the flat slab forming its roof 13, under the leer runway there are flues 14 connected to a cross sub iue 15 to give access to each separate flue and to the valves 15.1 for the regula-tion of the gas burners 15.2 supplied by gas from the pipe 15.3 to heat these flues. At the other end there is a cross flue 16 provided with a. damper 17 running under the leer runway and connecting the longitudinal Hues 14 to a stack 1S, this stack being provided with a fan 19 for the purpose of inducing a positivo draft therein. A flue 20 connects to the top of the leer runway through the chamber 43 by inlets 21 thence by the downtake to the stack 18. F lue 20 is provided with'a damper 23.

Across the full width of the leer building 10, a ceiling 24 is provided carried upon longitudinal channel irons. The ceiling commences toward the cool end of the leer way with a cross partition 25 built on the face of one 0f the trusses 11 and is coitinuous to the end of the building. The chamber formed by the ceiling and the roof of the building is designated by the numeral 26. The partition 25 has holes 27 provided with hinged damper doors 28 which are opera-tod by a usual window operating device consisting of levers 29, a horizontal shaft 30, a gearing 31, a vertical shaft 32 and an operating hand Wheel 33. Near the partition a liue pipe 34 is provided having openings 35 into the chamber 26. The other end of this flue connects through the wall to theoutside of the building with an opening 36. A damper 37 is provided to close the ilue from the outside air. At the opposite end of the chamber 26 exhaust fan 38 is provided with outlet 39 to the outside of the building.

In line with partition 25 or preferably between that point and the end of the runway, a cross partition 40 is built around the leer,

vacross the building to the sides and between the ceiling 24 and the roof of the leer 13, forming an air tight partition at this point inthe building. At the end of the leer runway a similar partiti-on 41 is constructed across the building up to its ceiling 24. Bctween these two bartitions 40 and 41 the roof 13 of the leer is removed `allowing free radiation from the sheet of glass designated by the numeral 42 to the ceiling 24 and free convection of air in this chamber designated by the numeral 43, formed by the walls 12 of the building, its ceiling 24 and the end parti tions 40 and 41, it being understood that there is a slot in partition 41 above the rods 6 through which the glass can pass. A stack 44 is connected to flues 14 by a cross flue 45 at an intermediate point 'of the runway. Figs. 6 and 7 illustrate a preferred form of glass carrying rod consisting of bars with asbestos bolted between them and on their upper surface as fully described in my copending application Serial No. 163,056.

The use and operation of the apparatus as an auxiliary for cooling the glass at lthe end of the leer is as follows. The fan 33 is put in operation and draws the air through the chamber 26. The dampers 28 being open. the air entering through Openings 27 will bc warmed from the radiatedvheat from the upper end of the leer and by the air heated by the furnaces 1 in the furnace hall 2 which will -be drawn through the leer building 10. In

its surface which can be maintained at approximately the same temperature as the roof of the building would be in the summer time. In the warmer Weather the dampers 28 are closed and the damper 37 to the intake pipe 34 is opened so that the air from the outside is taken into and through the chamber 26 thus cooling it and maintaining it at the approximate temperature of the outside air. In this way the surface t0 which they heat from the glass is radiated maybe maintained at a constant temperature summer and winter.

The flue 20 which usually is connected with the leer runway by means ofthe intake pipes 21, in this case being connected to the ceiling 24 pulls the air from the hot end of the leer through the ovens down the runway and thence tothe induced draft stack 18 where it is exhausted. This stack is used more especially for preparing the leer t0 receive the glass before casting and is shut down toa large extent when the leer is in operation. In the same manner the heat is drawn down the lues 14 under the runway through the cross Hue 16 and thence to the stack 18. These ues are used to heat the runway before casting and to maintain a subheat so that the rods 6, carrying the glass will be heated to approximately the same temperature as the glass. This has heretofore been necessary as otherwise if the rods are at a lower temperature than the glass, the glass being in contact with them will be Avented either causing small cracks or else stack 18 may be almost entirely closed so that no heat passes down the bottom fiues during the time of operation, it being immaterial if the rods are properly covered with a non-conducting material whether they are colder than the glass or not as theyl will not rapidly receive heat from it and therefore will not cause breakage. i

Stack 44 can be advantageously used to heat up the rods and brick work under certain conditions, instead of drawing the heat to the extreme end of the leer by stack 18, thus giving more favorable conditions for' cooling the glass at this end.

The vestibule 9' through which the car 7 passes carrying the sheet of glass is for the purpose of preventing a back draft of cold air from passing up through the chamber of the runway 42 by keeping one of the two doors at each end of it always closed.

It will be seen from the drawings that the Aceiling 24 is carried over the leer runway toward the hot end over the roof coveringI 13 of the leer to .a point on the leer runway where the temperature of the glass is greatly i reduced to that .temperature where it leaves the leer ovens. 1 This portion of the runway covering will radiate its heat to the ceiling 24 and in turn have the heat from the glass radi-ated to it. The temperature of the recipient of the hea-t will make a material difference at this point on account of the cooler condition of the glass, nearer to the ovens a difference of temperature of some 100 F. in the heat recipient would not make much -differencein the rate of cooling of the glass sheets which will be evident from considering the T4-t* ratios, but lwhere the temperature of the sheet is reduced to a comparatively low temperature, a difference corresponding to hat of summer to winter conditions in t `e temperature of the heat recipient will make a considerable difference in the rate -of radiation from. the heated body at the end of the leer the roof covering of the runway is removed so that the heat w-ill radiate directly from the glass sheet to the ceiling 9A. The glass will also be cooled by air circulation in this chamber coming in contact with it and coming in contact with the ceiling and walls of the building which will in turn absorb the heat from the air. The cooling by air contact is more eiective at the lower temperature than radiation and can be safely employed, provided lthat the surroundingI air is not too cold. The tempcrature in the chamber 43 is regulated by the air and gases dra-wn down the runway by means of the stack 18 .through the flue 20. The ceiling 24 is carried out over the chamber into which the glass enters after leaving the leer runway so that there is still further opportunity for keep-ing the glass `at an even temperature after it leaves the leer and until it is conveyed to the room Awhere it is cut and set inthe racks. l

vHaving thus described my inventlon, I claim: Y

1. In a plate glass annealing leer, the combination of a leer runway, a chamber in the building which contains the leer mlnway formed by the roof of the building and a ceiling, the ceiling having the function of being the receptive surface to .which the heat -from the glass is directly radiated for a portion of rthe runway, means to draw the ,heated air from the ,hotter end of the leer into thechamber through openings provided with controlling means, lan alternate Hue provided with a damper through which cooler air'can be drawn into the chamber,

` means for exhausting and producing a cur- Frbmthe parution wall 4o to .the wall 41 tinuous with and communicating with the leer runway, formed by the walls and ceiling of the building and cross walls in the building containing the runway, means for regulating the temperature in the chamber.

3. In comlbination with a plate glassannealing leer an auxiliary cooling device comprising an enlarged cooling chamber, oontinuous with and communicating with the leer runwayz formed by the walls .and ceiling of the building and cross walls in the building containing the runway, means for regufor the radiated heat from the glass, and

cross partition walls below the ceiling through which the leer runway passes forming separate chambers, means for regulating he temperatures progressive-ly in the chamers.

5. `In combination with a plate glass annealing'leer an enlarged cooling chamber continuous with and -communicating with the leer runway, formed by the walls and ceiling of the building and cross walls in the building containing the runway, having an ap-precialble drop in temperature, means to prevent unequal and rapid transference of heat to the carrying rods in the chamber by providing a material on their surface and in contact with the glass plate of relatively less conductivity than metal.

JAMES W. CRUIKSHANK. 

